This article investigates theoretically and empirically theeffects of competition for donors on the behavior of nonprofitorganizations. Theoretically, we consider a situation in whichnonprofit organizations use donations to produce some commodity,but the use of donations is only partially contractible. Themain results of the model indicate that an increase in competition(i) decreases the fraction of donations allocated to perquisiteconsumption and (ii) increases the fraction of donations allocatedto promotional expenditures. Moreover, the effects of competitionare magnified by the ability to contract on the use of donations.These hypotheses are tested with data on the expenditures ofnonprofit organizations in a number of subsectors where competitionis primarily local. We use across–metropolitan statisticalareas' variation to measure differences in competition and proxycontractibility by the importance of tangible assets, whichare more easily observed by donors. The estimated effects ofcompetition and contractibility are consistent with our model.